Vector impedance analyzers have been used for many years and are often used to provide very accurate and thorough antenna, component, and material evaluation. The impedance analyzer measures impedance (inductance, capacitance, and resistance) at one or more radio frequency (RF) ranges. The tool offers this data when using an AC signal level swept measurement function for evaluating an antenna or other device under actual operating conditions.
The one disadvantage of conventional, laboratory grade vector impedance analyzers is they are very expensive for those except corporations, institutional entities and government. In order to reduce cost, many analyzers do not measure a complex impedance (magnitude and phase) with sufficient accuracy, do not cover a wide impedance range with true phase angle nor do they distinguish between positive and negative reactance. Although some analyzers can calculate various parameters, the data is not displayed in a form that is easy for the operator to visualize.
Still other problems occur when an analyzer is used with an antenna system. When using the analyzer for this function, its performance can be significantly affected by extraneous radio signals received at the antenna that is being analyzed. While some lower cost devices may be suitable for some purposes, they are not appropriate for accurate measurements in the presence of strong, externally generated RF signals that inadvertently are input to the device. This might occur, for example, when the antenna is receiving strong broadcast stations operating at one frequency, while attempting to take accurate measurements for the antenna at a second frequency.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.